Figure3. Comparison between experimental data and model for (a)
diethyl ether and (b) ethanol for feed flow rate of 333 kmol/h
Figure 4a also shows that outlet concentration of diethyl ether exceeds
its inlet concentration due to its partial replacement by ethanol. This
phenomenon which is called “Roll-up” refers to the humps on the
diethyl ether breakthrough curve where its concentration exceeds the
feed condition. 18 According to the Yang book18, the “Roll-up” happens due to displacement of
weaker adsorbate (diethyl ether) by a strong one (ethanol). In the
beginning of adsorption, both diethyl ether and ethanol are adsorbed on
activated carbon surfaces since there are enough empty adsorption site
on the adsorbent. Figure 4b shows an interval of bed when surface of
activated bed is covered by ethanol and diethyl ether, further
adsorption of ethanol would replace the adsorbed diethyl ether so,
desorption of diethyl ether happens and competitive adsorption behaviors
exists in the bed intervals. Figure 4c shows that temperature of gas
stream is increased due to the nature of exothermic adsorption process
till bed saturation and then no more heat is released in which gas
temperature reaches to the feed temperature.